<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <style type="text/css">

        div{
            /*通过设置display: flex，把他转成弹性盒布局方式*/
            display: flex;
            width: 500px;
            height: 500px;
            border: 1px solid red;
            /*flex-direction: row;*/
            /*flex-direction: column-reverse;*/

        }
        span{
            display: inline-block;
            width: 33.33%;
            height: 100px;
            background-color: yellow;
        }
        .box2{
            order: 1;
            /*
            单独给某个子项目设定对齐的方式
              align-self: auto | flex-start | flex-end | center | baseline | stretch;
            */
            /*align-self: flex-end;*/
            align-self: center;
        }
    </style>
</head>
<body>
<div>
    <span>第一个</span>
    <span class="box2">第二个</span>
    <span>第三个</span>
</div>
</body>
</html>